1. Field of the Invention
The invention relates to a ball screw actuator for moving a door panel. More particularly, the invention relates to a ball screw door panel actuator and guide. Most particularly the invention relates to a ball screw actuator and alignment assembly.
2. Discussion of the Related Art
Spent nuclear fuel is contained in a steel cylinder, referred to as a canister. Canisters are loaded into a concrete vessel, known as storage overpack or overpack for long term storage. The overpack is a bottom loaded storage container made of reinforced concrete and steel plates. The upper portion of the storage overpack is a 13-foot diameter cylindrical reinforced concrete vessel with a 74-inch diameter inner steel cylindrical liner. The vessel is supported on a stack of circular steel plates. The door is a horizontally oriented steel plate located below the mid-plane of the stack of plates. The stack of plates comprising the storage overpack door and doorframe provides the structural support for the loaded canister inside the storage overpack. It also provides shielding from radiation emitted from the canister. The interface between the sliding door and doorframe is steel-on-steel and requires an externally mounted actuator to effect opening and closing of the door through an approximately 100-inch travel distance.
The inventor was confronted with a number of challenges including the size and weight of the sliding door, and the limited space available for the actuator to operate. A hydraulic piston actuator was considered but could not be used because of space limitations. The piston stroke length would double the space required to open the door. Also, a portable door actuator was required that did not use local facilities such as stanchion posts or building walls for anchoring.